1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and an electrophotographic apparatus employing the electrophotographic photosensitive member.
2. Related Background Art
Organic photosensitive members employing organic photoconductive material have come to be widely used as an electrophotographic photosensitive member in recent years. Conventional organic photosensitive members, because of the disadvantages of low sensitivity and low durability thereof, are useful only for low-speed electrophotographic apparatuses. The above disadvantages are being overcome with development of novel materials. Organic photosensitive members, however, have still disadvantages of deterioration of the properties on exposure to ozone or NO.sub.x. Since ozone and NO.sub.x are formed in an electrophotographic apparatus, a conventional photosensitive member, when used in an electrophotographic apparatus, is liable to cause deterioration of charge retention ability, decrease of sensitivity, smearing of images, and lowering of other performances.
In order to overcome such disadvantages and to maintain the electrophotographic characteristics, an antioxidant of a hindered phenol type, a phosphine type, or a sulfur type is added into the photosensitive layer to trap ozone and NO.sub.x. The addition of the antioxidant, however, tends to cause other disadvantages such as drop of initial sensitivity and rise of residual potential although the resistance to ozone and NO.sub.x is improved. Furthermore, when paper sheets are fed to the electrophotographic apparatus, the antioxidant which has trapped ozone or nitrogen oxides impedes carrier generation or carrier transportation in the photosensitive layer, thereby causing a decrease of sensitivity and chargeability disadvantageously.